I couldn't tell a difference in the taste bit wife said she could tell a difference between the snifter and the Reidel. Is that possible?
Can't think of a reason you would experience any difference in TASTE from one glass to another. Riedel used to make some preposterous claim that their various glasses directed the wine to certain sections of your mouth but they finally stopped trying to convince people that was possible.
You may get different aromatic qualities because remember, whatever you're smelling is some volatile compound and the different ones are more or less volatile than each other. Plus, the different glass shapes and sizes can concentrate them or let them escape more easily. That's in fact why you can't really design a glass for a particular grape - every time that grape is planted in a different vineyard, it's going to end up with slight differences in the juice. Now add in the different vintages, the different ambient yeasts and bacteria in the different wineries, the different fermentation and winemaking, not to mention the profound effects of aging, etc., and your Riesling, with its very characteristic aroma, is still going to be slightly different from one place to another and significantly different from one year to the next. So the "appropriate" glass in one instance is not necessarily so appropriate the next time. And then you have your personal physiology. So find a glass you like and buy that.
As far as lead goes, that's a more interesting story. You put lead oxide in the glass because it makes the glass softer and easier to cut and because it increases the clarity of the glass. It's obviously not really "crystal" because glass is an amorphous solid - it has no crystal structure. But when you cut the leaded glass, you can make it look like a crystal and that's what Ravenscroft called it when he popularized the technique, so that's the name.
However, small amounts of lead do in fact leech out into the wine. Remember, wine has plenty of acidity. Keep in mind though, that the amount of lead that might leech out into the glass in the normal course of drinking is miniscule. That's not the case if you store your wine in a decanter, but nobody really does that any more except in old movies where they keep the sherry or Port on the sideboard. Moreover, there are other compounds that can be used instead of lead oxide these days, so if you're concerned, just don't buy glasses with lead.
As far as altering the taste - I'm really skeptical that anyone can truly distinguish between 2 glasses, one with and one w/out lead, if they don't know beforehand which glass is which. Not saying it can't be done, and in fact, one can make a logical argument for it, but I would imagine that particular person would have a tongue that's as sensitive as a dog's nose. A super-taster to be sure.